1. Field of the Invention
The present invention relates to a tag access control system, a tag access control method and a tag access control program for controlling data communication between an IC tag provided in a moving article and a reader/writer.
2. Description of Related Art
In recent years, attention has been given to an RFID (Radio Frequency Identification) technology for recognizing an article using an IC tag. For example, in a factory or a distribution center, articles such as components or products are transported by a belt conveyor, a forklift, a hand truck or the like. By providing such articles with IC tags, it is possible to identify and manage the transported articles. In particular, passive-type IC tags require no batteries, so that the reduction of size and price can be achieved. Accordingly, they are expected to suit the identification and management of a large volume of articles.
The passive-type IC tag exchanges data by radio with a reader/writer having an antenna. An operation of detecting an IC tag and an operation of reading/writing data with respect to the IC tag by the reader/writer are controlled by an access control system. For instance, when an access control system transmits a command for allowing data communication with an IC tag to a reader/writer, the reader/writer executes the command and sends a result of the command to the access control system as a reply.
The access control system records a parameter for controlling a reader/writer beforehand, and sends a command to the reader/writer in accordance with the parameter. The parameter includes, for example, a timing parameter of detecting of an IC tag by the reader/writer or the number of IC tags detected collectively. For instance, the parameter indicating timing of detecting an IC tag is adjusted, whereby the timing of detecting the IC tag by a reader/writer can be controlled. Such a parameter should be set appropriately.
This is because it is important for the access control system to send an appropriate command at appropriate timing to a reader/writer in order to ensure the data communication with an IC tag. For instance, in the case where data communication is conducted with IC tags attached to a plurality of articles moving over a belt conveyor or the like, antennas of reader/writers are provided along a moving path of the articles. In this case, the access control system has to control the reader/writer so as to ensure detecting the IC tags and reading and writing data while the articles are within the communication ranges of the antennas.
To this end, JP 2004-82432 A, for example, has disclosed a label printer that controls a plurality of reader/writers, thereby reducing a writing failure rate while maintaining a recording velocity.